This application was published in English on Nov. 29, 2001 as International Publication Number WO 01/90800.
The present invention relates to a battery holder and, to a laser unit incorporating said battery holder.
The present inventor is a co-inventor of invention subject of U.S. Pat. No. 6,457,246 which describes a Laser Survey Apparatus typically in use for controlling or regulating the grade or alignment of tunnels in underground mining. The apparatus includes a sleeve that is grouted into a wall and a separate laser unit that can be selectively engaged and disengaged from the sleeve. The laser unit and sleeve co-operate so that when the laser unit is inserted into the sleeve it is automatically switched ON, and when withdrawn from the sleeve it is automatically switched OFF.
The laser unit includes a two-part body having a cylindrical portion and a shaft portion that can be screwed together. The cylindrical portion defines a cavity in which a battery and a laser module are housed. An electrical circuit for delivering an electric current from the battery to the laser module includes the cylindrical portion itself of the body.
When the battery in the apparatus runs flat the body is opened, the flat battery removed and a fresh battery inserted. The body of the apparatus is made from precision engineered metallic (ie electrically conductive) material. While the survey apparatus has found wide spread acceptance in the field problems arise from time to time if the body, and in particular the shaft becomes damaged. If the shaft becomes damaged it may not be received by the sleeve therefore making the laser unit unusable. While the sleeve portion can be replaced, due to the remote locations at which the apparatus is often used and the cost of the precision engineered shaft, the cost of repair and return of the apparatus may approach a substantial cost of the apparatus per se.
The present battery holder and laser unit incorporating same have arisen through developments made in order to overcome the abovementioned problem. While the battery holder was developed as part of the laser unit it can be incorporated in other battery operated devices.
According to a first aspect of the present invention there is provided a battery holder including at least:
a housing provided with a recess for receiving a battery;
a first electrical contact supported by the housing for making electrical contact with one terminal of the battery;
a second electrical contact supported by the housing for making electrical contact with a second terminal of the battery;
a third electrical contact supported by the housing; and,
a switch supported by the housing and in electrical contact with said third electrical contact, said switch switchable between an OFF state where the switch is spaced from the first electrical contact and an ON state in which the switch is in electrical contact with the first electrical contact thus placing the third electrical contact in electrical connection with said one terminal of the battery.
According to a further aspect of the present invention there is provided a battery holder including at least:
a housing-provided with a recess for receiving a plurality of batteries;
means for electrically connecting said batteries in series so that one terminal of one polarity of a first of said batteries is not connected to any other battery and a second terminal of an opposite polarity of a last of said batteries is not connected to any other battery;
a first electrical contact supported by the housing for making electrical contact with said one terminal of the first of said batteries;
a second electrical contact supported by the housing for making electrical contact with the second terminal of said last of said batteries;
a third electrical contact supported by the housing; and,
a switch supported by the housing and in electrical contact with said third electrical contact, said switch switchable between an OFF state where the switch is spaced from the said first electrical contact and an ON state in which the switch is in electrical contact with the first electrical contact thus placing the third electrical contact in electrical connection with said one terminal of the first of said batteries.
Preferably said switch is biased to the OFF state.
Preferably said switch includes a biased finger which is spaced from the first electrical contact when the switch is in the OFF state, said finger adapted to be pushed against said bias to contact said first electrical contact to change the state of the switch to the ON state.
Preferably said second and third electrical contacts are provided at the same end of said housing.
Preferably said first electrical contact is provided at an opposite end of said housing.
Preferably said housing is made from an electrically insulating material.
Preferably said housing is made from a plastics material.
Preferably said battery holder further includes electrically conductive bias means in electrical contact with the first contact and disposed to contact said first terminal of the battery to bias the second terminal into contact with the second electrical contact.
According to the present invention there is provided a laser unit comprising:
a body portion defining a cavity;
a hollow shaft portion extending from the body portion, said shaft portion having a first opening at one end leading to the cavity and a second opening at an opposite end;
a battery holder in accordance with the first or further aspect of the present invention disposed in the cavity;
a laser module disposed in the cavity and in electrical contact with the second and third electrical contacts;
a battery held within the battery holder; and,
a plunger slidably retained in the shaft, the plunger having one end adapted for abutment with the switch;
whereby, in use, insertion of a member into the second opening of the shaft slides the plunger toward the body actuating the switch to the ON state enabling electrical current to flow from the battery to the laser module.
Preferably said body portion and shaft portion are integrally formed.
Preferably said body portion and shaft portion are made from an electrically insulating material.
Preferably said laser unit includes a permanent sealing means for permanent sealing the cavity at an end of the body distant the shaft portion.